From a writing standpoint I just don't see how Jadzia appearing in half the episodes could have worked credibly short of, as I said, having the Dominion capture her, and that would still have felt strange from a viewer perspective. I've seen series where a main character was abducted (SG-1 did it a few times), but it was never half a season's worth of episodes. Farrell can say she wanted to be recurring, but it doesn't make sense for Jadzia to suddenly become recurring.
Alternate option is that she's off running unseen missions on Defiant, but that also smacks of weak storytelling.